Hu, F.B., M.J. Stampfer, 1999. Nut consumption and risk of coronary heart disease: a review of epidemiologic evidence. Current Atherosclerosis Reports. (1):205-10.
Traditionally nuts have been perceived as an unhealthy food because of their high fat content. However, recent accumulative evidence suggests that frequent consumption of nuts may be protective against coronary heart disease (CHD). So far, five large prospective cohort studies (the Adventist Health Study, the Iowa Women Health Study, the Nurses’ Health Study, the Physicians’ Health Study, and the CARE Study) have examined the relation between nut consumption and the risk of CHD and all have found an inverse association. In addition, several clinical studies have observed beneficial effects of diets high in nuts (including walnuts, peanuts, almonds, and other nuts) on blood lipids. The beneficial effects of nut consumption observed in clinical and epidemiologic studies underscore the importance of distinguishing different types of fat. Most fats in nuts are mono- and polyunsaturated fats that lower low-density lipoprotein cholesterol level. Based on the data from the Nurses’ Health Study, we estimated that substitution of the fat from 1 ounce of nuts for equivalent energy from carbohydrate in an average diet was associated with a 30% reduction in CHD risk and the substitution of nut fat for saturated fat was associated with 45% reduction in risk. Given the strong scientific evidence for the beneficial effects of nuts, it seems justifiable to move nuts to a more prominent place in the United States Department of Agriculture Food Guide Pyramid. Regular nut consumption can be recommended in the context of a healthy and balanced diet.
Fraser, G.E., 1999. Nut consumption, lipids and risk of a coronary event. Clin Cardiol. 22(suppl. III):11-5.
In the past, many have avoided nuts because of their high fat content. The Dietary Approaches to Stop Hypertension (DASH) diet, however, recommends regular consumption of this food along with seeds and dried beans (4-5 servings per week) as part of a diet to control hypertension. Nuts are nutrient-dense and most of their fat is unsaturated. They are also perhaps the best natural source of vitamin E and are relatively concentrated repositories of dietary fiber, magnesium, potassium, and arginine, the dietary precursor of nitric oxide. Human feeding studies have demonstrated reductions of 8-12% in low-density lipoprotein (LDL) cholesterol when almonds and walnuts are substituted for more traditional fats. Other studies show that macadamias and hazelnuts appear at least as beneficial as fats in commonly recommended diets. Whether consuming modest quantities of nuts daily may promote weight gain is not known with certainty, but preliminary data suggest that this is unlikely. Four of the best and largest cohort studies in nutritional epidemiology have now reported that eating nuts frequently is associated with a decreased risk of coronary heart disease of the order of 30-50%. The findings are very consistent in subgroup analyses and unlikely to be due to confounding. Possible mechanisms include reduction in LDL cholesterol, the antioxidant actions of vitamin E, and the effects on the endothelium and platelet function of higher levels of nitric oxide. Although nuts may account for a relatively small percentage of dietary calories, the potential interacting effects of these factors on disease risk may be considerable.
Chisolm, A., J. Mann, M. Skeaff, C. Franpton, W. Sutherland, A. Duncan, S. Tiszavari, 1998. A diet rich in walnuts favorably influences plasma fatty acid profile in moderately hyperlipidemic subjects. Eur J Clin Nutr. 52:12-6.
Objective: To compare two low fat diets one rich in walnuts on parameters of lipid metabolism in a group of hyperlipidemic subjects. Design: A randomized cross over study. Setting: Department of Human Nutrition, University of Otago, Dunedin, New Zealand Subjects: Twenty one men with mean (s.d) levels of total and LDL cholesterol of 6.58 (0.60) and 4.63 (0.58) respectively. Interventions: For two periods of four weeks subjects were asked to consume two low fat diets (fat 30% total energy), one containing, on average, 78 g=d walnuts. Walnuts obtained through Lincoln University and the Walnut Growers Group (South Canterbury). Results: Participants reported a higher total fat intake on the walnut diet (38% compared with 30% on the low fat diet P<0.01) The most consistent change in fatty acid profile of triacylglycerol, phospholipid and cholesterol ester on the walnut diet was a significant (P<0.01) increase in linoleic acid. Triacylglycerol linolenate also increased significantly (P<0.01). Total and LDL cholesterol were lower on both experimental diets than at baseline, 0.25 mmol/l and 0.36 mmol/l respectively on the walnut diet and 0.13 mmol/l and 0.20 mmol/l respectively on the low fat diet. High density lipoprotein cholesterol was higher on both the walnut and low fat diets when compared to baseline (0.15 mmol/l and 0.12 mmol/l, respectively). When comparing the walnut and low fat diets only apo B was significantly lower (P<0.05) on the walnut diet. Conclusions: Despite an unintended increase in the total fat intake on the walnut diet, fatty acid profile of the major lipid fractions showed changes which might be expected to reduce risk of cardiovascular disease. The reduction of apolipoprotein B suggests a reduction in lipoprotein mediated risk, the relatively low myristic acid content of both diets perhaps explaining the absence of more extensive differences in lipoprotein levels on the two diet
Spiller, G.A., D.A.J. Jenkins, O. Bosello, J.E. Gates, L.N. Cragen, B. Bruce, 1998. Nuts and plasma lipids: an almond-based diet lowers LDL-C while preserving HDL-C. J Am Coll Nutr. 17(3):285-90.
OBJECTIVE: To compare lipid-altering effects of an almond-based diet with an olive oil-based diet, against a cheese and butter-based control diet. METHODS: Forty-five free-living hyperlipidemic men (n = 12) and women (n = 33) with a mean plasma total cholesterol (TC) of 251 +/- 30 mg/dL followed one of three diets; almond-based, olive oil-based, or dairy-based for 4 weeks. Total fat in each diet was matched, and the study-provided sources of fat comprised the major portion of fat intake. RESULTS: Reductions in TC and low-density lipoprotein-cholesterol (LDL-C) between the three groups were significantly different from the almond group (both p < 0.001). Within group analysis revealed that the almond-based diet induced significant reductions in TC (p < 0.05), LDL-C (p < 0.001), and the TC:HDL ratio (p < 0.001), while HDL-C levels were preserved. TC and HDL-C in the control diet were significantly increased from baseline (both p < 0.05), while the olive oil-based diet resulted in no significant changes over the study period. Weight did not change significantly. CONCLUSION: Results suggest that the more favorable lipid-altering effects induced by the almond group may be due to interactive or additive effects of the numerous bioactive constituents found in almonds.
Hu, F.B., M.J. Stampfer, J.E. Manson, E.B. Rimm, G.A. Colditz, B.A. Rosner, F.E. Speizer, C.H. Hennekens, W.C. Willett, 1998. Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study. British Med J. 317:1341-5.
OBJECTIVE: To examine the relation between nut consumption and risk of coronary heart disease in a cohort of women from the Nurses’ Health Study. DESIGN: Prospective cohort study. SETTING: Nurses’ Health Study. SUBJECTS: 86 016 women from 34 to 59 years of age without previously diagnosed coronary heart disease, stroke, or cancer at baseline in 1980. MAIN OUTCOME MEASURES: Major coronary heart disease including non-fatal myocardial infarction and fatal coronary heart disease. RESULTS: 1255 major coronary disease events (861 cases of non-fatal myocardial infarction and 394 cases of fatal coronary heart disease) occurred during 14 years of follow up. After adjusting for age, smoking, and other known risk factors for coronary heart disease, women who ate more than five units of nuts (one unit equivalent to 1 oz of nuts) a week (frequent consumption) had a significantly lower risk of total coronary heart disease (relative risk 0.65, 95% confidence interval 0.47 to 0.89, P for trend=0.0009) than women who never ate nuts or who ate less than one unit a month (rare consumption). The magnitude of risk reduction was similar for both fatal coronary heart disease (0.61, 0.35 to 1.05, P for trend=0.007) and non-fatal myocardial infarction (0.68, 0.47 to 1.00, P for trend=0.04). Further adjustment for intakes of dietary fats, fiber, vegetables, and fruits did not alter these results. The inverse association persisted in subgroups stratified by levels of smoking, use of alcohol, use of multivitamin and vitamin E supplements, body mass index, exercise, and intake of vegetables or fruits. CONCLUSIONS: Frequent nut consumption was associated with a reduced risk of both fatal coronary heart disease and non-fatal myocardial infarction. These data, and those from other epidemiological and clinical studies, support a role for nuts in reducing the risk of coronary heart disease.
Alphan, E., M. Pala, F. Ackurt, T. Yilmaz, 1997. Nutritional composition of hazelnuts and its effects on glucose and lipid metabolism. In: Kosal AI, Oky Y, Gunes NT, eds. Proceedings of the Fourth International Symposium on Hazelnut. Acta Hort. 445:305-10.
Turkey holds the first place is the world with respect to hazelnut production and export. Besides its economic importance, the high nutritional value of hazelnut makes it a special food. Hazelnuts are rich in protein, complex carbohydrates, dietary fiber, iron, calcium, potassium and vitamin E. Nutritional analyses conducted in our laboratories have revealed a high protein content (16.9%). Its protein quality (66.6%) is also high in comparison to many proteins of plant origin. It appeared to be one of the best sources of plant origin for iron (5.8 mg/100g), calcium (160.0 mg/100 g), and zinc (2.2 mg/100g), which are the most important minerals for growth and development. Hazelnuts were also found to be rich in potassium(655 mg/100g), which is necessary for nerve stimulation and functioning of muscle tissue. Hazelnuts were found to be good sources for vitamins B1 (0.33 mg/100g), and B2 (0.12 mg/100g), and very good sources for vitamin B6 (0.24 mg/100g) and Vitamin E (31.4 mg/100g). VitaminsB2 and B6 are especially important nutrients for the school-age children. The hazelnut is also the second best source of vitamin E after plant oils. This vitamin is essential for the normal functioning of muscle tissue and the reproduction system. It protects the organism against cancer. Vitamin E also prevents the hemolysis of erythrocytes, and thus protects the body against anemia. Chemical and nutritional compositions of hazelnut are shown in table. 1 (Pala et al., 1995). The average fat content of hazelnuts analyzed in our laboratories was found to be 62.7% and 82% of this high yield was assessed to be oleic acid. This monounsaturated fatty acid was shown by many workers to increase the level of high density lipoprotein (HDL), in blood. HDL, in turns, lowers blood cholesterol and thus protects against atherosclerosis. According to a long term survey conducted in the United States over 20,000 subjects (Loma Linda University, 1990), the risk of death from coronary heart disease is lowered by half in people consuming nuts at least once a day as compared with those who don’t. Because of their chemical and nutritional compositions, hazelnuts have potential beneficial health effects. Diet is a cornerstone of therapy for patients with non-insulin-dependent diabetes mellitus (NIDDM). The goal of diet therapy in patients with diabetes is not only to improve control of hyperglycemia but also to reduce the risk of coronary heart disease by optimizing plasma lipid levels. Currently recommended high carbohydrate, low fat diets increase triglyceride and lower high density lipoprotein (HDL) cholesterol concentrations (Garg et al., 1988; Koskinen et al., 1992
Jenkins, D.J.A., D.G. Popovich, C.W.C. Kendall, E. Vidgen, N. Tariq, T.P.P. Ransom, T.M.S. Wolever, V. Vuksan, C.C. Mehling, D.L. Boctor, C. Bolognesi, J. Huang, R. Patten, 1997. Effect of a diet high in vegetables, fruit, and nuts on serum lipids. Metabolism. 46(5):530-7.
We assessed the effect of a diet high in leafy and green vegetables, fruit, and nuts on serum lipid risk factors for cardiovascular disease. Ten healthy volunteers (seven men and three women aged 33 +/- 4 years [mean +/- SEM]; body mass index, 23 +/- 1 kg/m2) consumed their habitual diet (control diet, 29% +/- 2% fat calories) and a diet consisting largely of leafy and other low-calorie vegetables, fruit, and nuts (vegetable diet, 25% +/- 3% fat calories) for two 2-week periods in a randomized crossover design. After 2 weeks on the vegetable diet, lipid risk factors for cardiovascular disease were significantly reduced by comparison with the control diet (low-density lipoprotein [LDL] cholesterol, 33% +/- 4%, P < .001; ratio of total to high-density lipoprotein [HDL] cholesterol, 21% +/- 4%, P < .001; apolipoprotein [apo] B:A-I, 23% +/- 2%, P < .001; and lipoprotein (a) [Apo (a)], 24% +/- 9%, P = .031). The reduction in apo B was related to increased intakes of soluble fiber (r = .84, P = .003) and vegetable protein (r = -.65, P = .041). On the vegetable compared with the control diet, the reduction in total serum cholesterol was 34% to 49% greater than would be predicted by differences in dietary fat and cholesterol. A diet consisting largely of low-calorie vegetables and fruit and nuts markedly reduced lipid risk factors for cardiovascular disease. Several aspects of such diets, which may have been consumed early in human evolution, have implications for cardiovascular disease prevention.
Bruce, B., G.A. Spiller, J.W. Farquhar, 1997. Effects of a plant-based diet rich in whole grains, sun-dried raisins and nuts on serum lipoproteins. Veg Nutr. 1(2):58-63.
After four weeks of a diet rich in whole grains, sun-dried raisins and nuts, researchers saw an improvement in total and LDL cholesterol levels in 15 adults with elevated blood lipids. Both improved colon function and increased feelings of fullness were also seen with this plant-based diet containing unrefined, minimally processed foods. Further research is needed to identify additional positive effects of this diet on heart disease risk factors.
Bruce, B., G.A. Spiller, 1997. Nuts and healthy diets. Veg Nutr: An Int J. 1(1):12-16.
Since ancient times, nuts and seeds have been considered healthful foods worldwide. This paper looks at the history and composition of a variety of nuts, and their effects on health, particularly heart disease. According to the authors, “nuts are an under-recognized and under-consumed food in modern diets.” Nuts provide a variety of nutrients and can play an important role in the diet, especially for those who are eating a more plant-based diet.
Appel, L.J., et al., 1997. A clinical trial of the effects of dietary patterns on blood pressure. NEJM.336:1117-24.
Background It is known that obesity, sodium intake, and alcohol consumption influence blood pressure. In this clinical trial, Dietary Approaches to Stop Hypertension, we assessed the effects of dietary patterns on blood pressure. Methods We enrolled 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic blood pressures of 80 to 95 mm Hg. For three weeks, the subjects were fed a control diet that was low in fruits, vegetables, and dairy products, with a fat content typical of the average diet in the United States. They were then randomly assigned to receive for eight weeks the control diet, a diet rich in fruits and vegetables, or a “combination” diet rich in fruits, vegetables, and low-fat dairy products and with reduced saturated and total fat. Sodium intake and body weight were maintained at constant levels. Results At base line, the mean (±SD) systolic and diastolic blood pressures were 131.3±10.8 mm Hg and 84.7±4.7 mm Hg, respectively. The combination diet reduced systolic and diastolic blood pressure by 5.5 and 3.0 mm Hg more, respectively, than the control diet (P<0.001 for each); the fruits-and-vegetables diet reduced systolic blood pressure by 2.8 mm Hg more (P<0.001) and diastolic blood pressure by 1.1mm Hg more (P=0.07) than the control diet. Among the 133 subjects with hypertension (systolic pressure, ≥140 mm Hg; diastolic pressure, ≥90 mm Hg; or both), the combination diet reduced systolic and diastolic blood pressure by 11.4 and 5.5 mm Hg more, respectively, than the control diet (P<0.001 for each); among the 326 subjects without hypertension, the corresponding reductions were 3.5 mm Hg (P<0.001) and 2.1 mm Hg (P=0.003). Conclusions A diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure. This diet offers an additional nutritional approach to preventing and treating hypertension.
